484 



MARINE PRODUCTS OF COMMERCE 



the centrifuge enters a storage tank from which it is fed directly into the evapora- 

 tors, where it is concentrated. 



The suspended particles of fish flesh recovered by the centrifuge are higher 

 in protein value, especially in riboflavin, than those discharged from the presses. 

 In some plants these are added to the press-cake meal to enrich it; in others they 



{Courtesy Sharpies Corp.) 



Fig. 22-11. Super-D-Canter removes fish meal from acidulated stickwater. Photo shows 



internal construction. 



are dried separately and sold at a price about IM to 2 times more than that of the 

 usual plant meal. The recovery of this material amounts to approximately 10 

 pounds per 1 ton of the fish processed in the general operation of the plant. 



Concentration of Stickwater. The concentration of the stickwater is completed 

 by means of vacuum evaporators, operated in sets of three or more units. The two 

 principal designs for these evaporator units are the horizontal and vertical; their 

 names derive from the position of the steam tubes which furnish the heat for 

 concentrating the liquors. Both types are used in stickwater plants. Usually a 

 decision as to the type to be installed in a particular plant depends upon a 

 number of engineering factors. Available floor space is one of the most important 

 of these. 



Each of the evaporator units is divided into two entirely separate compartments : 

 first, a series of tubes through which steam circulates to furnish heat for the 

 evaporation of the excess water in the liquor; second, the compartment contain- 



